What is the relationship between body and mind?
Descartes reset Western philosophy in the 17th century by questioning every dogma bequeathed to him, then sought to build his philosophy up rationally, starting from the first thing he thought he could be certain of, his famous, 'I think therefore I am'. Shortly afterwards, he gives his reasoning for why he thinks that the body and the mind must be made out of fundamentally different substances, the body from matter and the mind from something different, a view called mind-body dualism (or Cartesian dualism in particular). The passage in which he reasons this is given at: https://tinyurl.com/ydb73lp7 (please try to read through this before attending the session).
Though Descartes had repealed much of the Thomist (Christian) philosophy of the time, he retained an argument for the existence of god and also for a separation of body and mind.

This ideas have fed through to common expressions, e.g. about souls, spirits and ghosts (though we can't hold Descartes entirely responsible), ideas which are common in non-Western cultures too (this the Dhama in Buddhism or the Bhrama in Hinduism).
But there are some tricky problems in​ explaining dualism: just quite how do the mind and body interact? For Descartes, the small penal gland at the centre of the brain was the point at which the body interacted with the soul. Another issue is how one can know about the external world from one's seat in the mind: might it all be an illusion? Descartes had to resort to relying on a good god to refute this proposition.
Today, many people tend to think of things differently to Descartes, suggesting that mind and body are not made of different things: they are the same thing, or that the mind is generated from the body. These are 'monist' theories and can be materialist (in the sense that 'matter' is the only ultimately-existing thing). It is often the materialist premise that starts people's reasoning: since all that there is is matter, mind cannot be a separate thing, it must be generated by matter or equivalent to it. (Sometimes, the reasoning is taken a step further by taking the premise that there is no god, therefore all that there is is the material world.)
Do these ideas refute Descartes ideas? If so, does this mean that there is a problem with Descartes reasoning?